This invention generally relates to stents and maintaining a body passageway open.
Bladder outlet obstruction is a urological disorder. In males, this urological disorder can be caused by an enlarged prostate that constricts the prostatic urethra. Such disorders include, for example, benign prostatic hyperplasia or prostatic carcinoma. The prostatic urethra is a section of the urethra that passes through the prostate. Bladder outlet obstruction is associated with a plurality of undesirable symptoms such as difficulties in urination, strongly reduced capacity to urinate, an increased desire to urinate, or the complete inability to urinate which may lead to severe renal disorders.
To eliminate these symptoms, medical devices that attempt to maintain an open passageway through the prostatic urethra have been developed. One of the medical devices developed for this purpose is a Foley catheter. The Foley catheter is a tube that extends from the patient""s bladder to a collection bag located outside of the patient""s body. The Foley catheter provides constant drainage, but it does not allow the patient to control his voiding function.
Some indwelling prostatic stents seek to allow the patient to control their voiding function while also retaining the prostatic urethra open. For example, U.S. Pat. No. 5,766,209 describes a prosthesis that contains two tubular elements that are intended to be located on either side of the patient""s external sphincter, and a connector that is intended to be held in the orifice of the external sphincter.
Following conclusion of the treatment of the urological disorder (for example, when patency of the urethra is restored), a medical professional is generally required to remove an indwelling prostatic stent either transurethreally or endoscopically. A partially absorbable stent which can be implanted following a surgical procedure and be easily removed by the patient would obviate the need for a patient to return to the doctor for removal of the stent.
The invention generally relates to draining fluid from the bladder of a patient with a stent. Devices and methods according to the invention are typically used in the treatment for patients suffering from bladder outlet obstruction to address and relieve urinary retention. It is an object of the invention to maintain the urethra open and able to pass fluids from the bladder while also allowing normal operation of the patient""s external sphincter such that the patient has control over the retention and discharge of urine (and/or other fluids) from the bladder. It is another object of the invention to resist migration of a device placed within the patient""s urinary system, and also to prevent or reduce the attraction of blood clots (and/or other debris) when the device is placed and used within the patient. It is a further object of the invention to permit ease of removal of the device by the patient when patency of the lumen is restored.
It is noted initially that the directional terms proximal and distal require a point of reference. As used herein, the point of reference is from the perspective of the body of the patient. Therefore, the term proximal refers to a direction that points into the body of the patient, whereas the term distal refers to a direction that points out of the patient""s body.
In one aspect, the invention features a medical device for use within a body lumen of a patient comprising a first coil, a second coil, and a connecting segment. When placed within the body of the patient the first coil comprises a plurality of windings defining a first lumen and locatable on the proximal side of the external sphincter and a distal end terminating on the proximal side of the external sphincter. The second coil comprises a plurality of windings defining a second lumen and locatable on the distal side of the external sphincter and a proximal end terminating on the distal side of the external sphincter. The connecting segment is locatable in the external sphincter when the device is placed within the body of the patient and is disposed between and couples together the first and second coils. The medical device can have a removal segment attached to a proximal end of the first coil. The removal segment can be disposed within the first lumen and/or the second lumen.
In one embodiment, the first coil, the second coil, and the connecting segment further comprise an inner core and an outer coating covering at least a portion of the inner core. The inner core may be formed from a biocompatible material. In one embodiment, the outer coating is formed from a material that is absorbed into the lumen of a patient at a predetermined degradation rate. The outer coating may be formed from polyglycolic acid, polylactic acid, a polymer, or a polymid. The outer coating may also comprise a pharmaceutical.
In another embodiment, the windings of the first coil and the second coil are sized and configured to progressively uncoil from the proximal end of the first coil to a distal end of the second coil upon application of a continuous tensile force to the removal segment. The proximal end of the first coil may be formed into a variety of shapes to permit atraumatic entry of the medical device into the body of the patient. In one embodiment, the proximal end of the first coil is a frusto-conical shape. In another embodiment, the proximal end of the first coil and the distal end of the second coil include one or more hooks to permit connection to a delivery system.
In one embodiment, the windings of the first coil and the second coil are separated from each other by a distance in the range of from about 0.5 millimeters to about 10 millimeters. In one embodiment, the cross-sectional area of the outer coating is in the range from about 0.0079 millimeters2 to about 7.1 millimeters2.
Another aspect of the invention features a medical device for use within a body lumen of a patient comprising an inner core and an outer coating layered upon a portion of the inner core. The inner core includes a first coil defining a first lumen and having a proximal end and a distal end. The inner core also includes a second coil defining a second lumen having a proximal end and a distal end. The outer coating provides structural support to the first lumen and the second lumen of the inner core when placed with a body lumen of a patient. The inner core further comprises a plurality of spaced coil windings being sized and configured for placement and retention substantially within the urethra of a patient. A connecting segment is disposed between and couples together the first coil and the second coil. In one embodiment, the medical device is of unitary construction. The medical device can also have a removal segment attached to the proximal end of the first coil. The removal segment can be disposed within the first lumen and/or the second lumen.
The inner core may be formed from a biocompatible material. The outer coating may be formed from a material that loses structural integrity during hydration and may be absorbed into the lumen of a patient at a predetermined degradation rate. The outer coating may be formed from polyglycolic acid, polylactic acid, a polymer, or a polymid. The outer coating may also comprise a pharmaceutical.
In another embodiment, the windings are sized and configured to progressively uncoil from the proximal end of the first coil to the distal end of the second coil upon application of a continuous tensile force to the removal segment. The proximal end of the first coil may be formed into a variety of shapes to permit atraumatic entry of the medical device into the body of the patient. In one embodiment, the proximal end of the first coil is a frusto-conical shape. In another embodiment, the proximal end of the first coil and the distal end of the second coil includes one or more hooks to permit connection to a delivery system. In one embodiment, the windings of the first coil and the second coil are separated by a distance in the range of from about 0.5 millimeters to about 10 millimeters. In one embodiment, the cross-sectional area of the outer coating is in the range of from about 0.0079 millimeters2 to about 7.1 millimeters2.
Another aspect of the invention, features a method of maintaining the patency of a patient""s urethra. The method includes supporting the prostatic section of the urethra with a first coil defining a first lumen and locatable on the proximal side of the external sphincter, supporting the bulbar section of the urethra with a second coil defining a second lumen and locatable on the distal side of/the external sphincter, and permitting substantially normal constriction of the external sphincter with a substantially uncoiled segment coupling the first coil and second coil.
The method can include providing a delivery system comprising a first element and a second element. The first element has an outer diameter smaller than the diameters of the first coil and the second coil and includes a first end, a second end, and a connection member extending out from the first end. The second element includes a first end, a second end, and a connection member extending out from the first end with the first and/or the second elements of the delivery system being rotatable. In one embodiment, the connection member of the first element comprises an arm extending radially outward from the first end and includes an opening sized to receive a hook extending from the proximal portion. In another embodiment, the connection member of the second element comprises an arm extending radially outward from the first end and includes an opening sized to receive the hooks extending from the proximal portion of the first segment and the distal end of the second segment.